Joint Collaborative Team on Video Coding (jct-vc)

5.8Non-deblocking loop filters

5.8.1Syntax for SAO and ALF in APS

JCTVC-I0171 Refinement for SAO and ALF syntax in the APS [S. Esenlik, M. Narroschke, T. Wedi (Panasonic)]

No longer relevant due to removal of SAO parameters from the APS.

JCTVC-I0515 Cross-check report of JCTVC-I0171 [O. Bici, K. Ugur (Nokia)] [late]

5.8.2Adaptive loop filter

JCTVC-I0157 AHG6: Baseline options for ALF [Yu-wen Huang (MediaTek)]
JCTVC-I0493 Crosscheck of Option 2 (RA) and independent ALF chroma control of AHG6: Baseline options for ALF (JCTVC-I0157) [M. Budagavi (TI)] [late]
JCTVC-I0169 Grid displacements for ALF [S. Esenlik, M. Narroschke, T. Wedi (Panasonic)]
JCTVC-I0527 Cross-check of JCTVC-I0169 - Grid displacements for ALF [A. Fuldseth (Cisco)] [late]
JCTVC-I0215 AHG6: ALF baseline Option 2 BA with reduced number of filters [P. Lai, F. C. A. Fernandes (Samsung)]
JCTVC-I0525 AHG6: Crosscheck on ALF baseline Option 2 BA with reduced number of filters (JCTVC-I0215) [T. Tsukuba, T. Ikai (Sharp)] [late]
JCTVC-I0287 Non-CE2: Reduced coefficient precision for ALF complexity reduction [F. Kossentini, M. Horowitz, H. Guermazi, N. Mahdi (eBrisk Video)]
JCTVC-I0289 Non-CE2: A cross 7x5 shape for ALF complexity reduction [F. Kossentini, M. Horowitz, H. Guermazi, N. Mahdi (eBrisk Video)]
JCTVC-I0424 Non-CE2: Cross check of ALF filter modification (JCTVC-I0287, JCTVC-I0289) by Qualcomm [I. S. Chong, M. Karczewicz (Qualcomm)]
JCTVC-I0290 AHG6: Restriction on ALF filtering area [T. Ikai (Sharp)]
JCTVC-I0214 AHG6: Cross-check of JCTVC-I0290 on restriction on ALF filtering area [P. Lai, F. C. A. Fernandes (Samsung)] [late]
JCTVC-I0346 AHG6: Simplification of ALF filter coefficients coding [M. Budagavi (TI)]
JCTVC-I0488 AHG6: Cross-check of simplification of ALF filter coefficients coding (JCTVC-I0346) [T. Yamakage, T. Itoh, T. Watanabe (TOSHIBA)] [late]
JCTVC-I0363 AHG6: Comparison of block adaptive (BA) and region adaptive (RA) ALF [I. S. Chong, K. Sanjeev, M. Karczewicz (Qualcomm)]

In this document, analysis is reported on the difference between region adaptive (RA) and block adaptive (BA) ALF. It was claimed that even though RA mode is conceptually less complex than BA mode, BA mode has desirable properties such as better coding gain and visual quality. Also the complexity difference between the two modes is asserted to be minor.

Objective loss by RA is 0.2%/0.4%/0.1%/0.2% for AI/RA/LB/LP.

The loss is larger for class A test sequences.

It was claimed that BA has better visual performance in smaller regions and at thin lines. (The "People on street" sequence is mentioned as an example of this.)

The contributor and one more expert asserted that in terms of hardware complexity the issue is not critical

Two experts expressed concerns that filter switching at the 4x4 level is critical.

The question was asked whether the additional complexity of BA is critical compared to the overall complexity of ALF. This may be implementation dependent.

Action taken: See section on CE2.

JCTVC-I0381 ALF filter coefficients distribution and modifications to coding [M. Budagavi (TI)]
JCTVC-I0386 Study of ALF shapes [M. Budagavi (TI)]
JCTVC-I0454 AHG6: Test results on region adaptive ALF with 64 regions [T. Yamakage, T. Itoh, T. Watanabe, T. Chujoh (TOSHIBA), C.-Y. Tsai, C.-Y. Chen, C.-M. Fu, Y.-W. Huang, S. Lei (MediaTek), I. S. Chong, M. Karczewicz (Qualcomm)] [late]

5.8.3Sample adaptive offset

JCTVC-I0066 Non-CE1: Improved edge offset coding for SAO [A. Minezawa, K. Sugimoto, S. Sekiguchi (Mitsubishi)]
JCTVC-I0453 Non-CE1: Cross-verification report of improved edge offset coding for SAO (JCTVC-I0066) [S. Matsuo, M. Matsumura, S. Takamura, A. Shimizu (NTT)] [late]
JCTVC-I0073 SAO simplification [K. Andersson, P. Wennersten, R. Sjöberg (Ericsson)]
JCTVC-I0316 Cross-check of SAO Simplification in JCTVC-I0073 [D.-K. Kwon, W.-S. Kim (TI)] [late]
JCTVC-I0130 Simplification on SAO syntax [T. Lee, E. Alshina, J. Park (Samsung)]
JCTVC-I0211 Non-CE1: Crosscheck of Samsung's simplification on SAO syntax in JCTVC-I0130 [C.-M. Fu, Y.-W. Huang (MediaTek)] [late]
JCTVC-I0137 AHG6: Non-CE1: Removing boundary artefacts by weighted offset values for SAO [T.Matsunobu, T.Sugio, H.Sasai, T.Nishi (Panasonic)]
JCTVC-I0400 Non-CE1: Cross-check by Samsung for Panasonic's removing boundary artefacts by weighted offsets (JCTVC-I0137) [E. Alshina (Samsung)] [late]
JCTVC-I0162 Non-CE1, Test2.1: Reduced number of band offsets per LCU [E. Alshina, A. Alshin, J. H. Park (Samsung), I.-S. Chong, M. Karczewicz (Qualcomm), C.-M. Fu, Y.-W. Huang, S. Lei (MediaTek)]
JCTVC-I0168 Non-CE1: Bug-fix of offset coding in SAO interleaving mode [C.-M. Fu, Y.-W. Huang, S. Lei (MediaTek)]
JCTVC-I0191 Cross verification of JCTVC-I0168 on non-CE1 results from MediaTek on SAO [G. Laroche, T. Poirier, P. Onno (Canon)] [late]
JCTVC-I0172 Non-CE1: Prohibition against merging across slice/tile boundaries in SAO [C.-M. Fu, C.-Y. Tsai, Y.-W. Huang, S. Lei (MediaTek)]
JCTVC-I0183 Non-CE1: On SAO parameters reduction for Chroma [G. Laroche, T. Poirier, C. Gisquet, P. Onno (Canon)]
JCTVC-I0413 Non-CE1: Cross-check of On SAO parameters reduction for Chroma (JCTVC-I0183) [K. Andersson (Ericsson)] [late]
JCTVC-I0184 Non-CE1: Encoder modification for SAO interleaving mode [G. Laroche, T. Poirier, P. Onno (Canon)]
JCTVC-I0401 Non-CE1: Cross-check by Samsung for encoder modification for SAO interleaving mode from Canon (JCTVC-I0184) [E. Alshina (Samsung)] [late]
JCTVC-I0185 Non-CE1: On SAO fixed offsets [G. Laroche, T. Poirier, P. Onno (Canon)]
JCTVC-I0202 Non-CE1: Crosscheck of Canon's SAO fixed offsets in JCTVC-I0185 [C.-M. Fu, Y.-W. Huang (MediaTek)] [late]
JCTVC-I0193 Non-CE1: LCU SAO Enable Flag Coding [W.-S. Kim, D.-K. Kwon (TI), I. S. Chong, M. Karczewicz (Qualcomm)]
JCTVC-I0405 Non-CE1: Cross-check of TI and Qualcomm proposal (JCTVC-I0193) for LCU SAO Enable Flag Coding [J. Min, E. Alshina, J. H. Park (Samsung)] [late]
JCTVC-I0095 Non-CE1: Cross-check of LCU SAO enable flag coding [A. Fuldseth (Cisco)] [late]
JCTVC-I0199 Non-CE1: Decoupling SAO on/off from SAO type with neighbour-based contexts [C.-W. Hsu, C.-M. Fu, T.-D. Chuang, Y.-W. Huang, S. Lei (MediaTek)]
JCTVC-I0492 Cross-verification of JCTVC-I0199 on decoupling SAO on/off from SAO type with neighbour-based contexts [J. Min, E. Alshina, J. Park (Samsung)] [late]
JCTVC-I0200 Non-CE1: SAO Parameter Estimation Using Non-deblocked Pixels in Interleaving Mode [W.-S. Kim (TI)]
JCTVC-I0385 Non-CE1: Crosscheck of SAO parameter estimation using non-deblocked pixels in interleaving mode in JCTVC-I0200 [C.-M. Fu, Y.-W. Huang (MediaTek)] [late]
JCTVC-I0246 SAO Type Coding Simplification [E. Maani (Sony), K. Minoo, D. Baylon (Motorola), E. Alshina (Samsung)]

See notes in section discussing I0602.

JCTVC-I0540 Cross-check of JTVC-I0246 on SAO type coding simplification [D.-K. Kwon, W.-S. Kim (TI)] [late]
JCTVC-I0247 Continuity in Band Offset SAO [E. Maani, O. Nakagami (Sony)]
JCTVC-I0431 Non-CE1: Cross check of continuity in Band Offset SAO (JCTVC-I0247) [I. S. Chong, M. Karczewicz (Qualcomm)] [late]
JCTVC-I0261 Non-CE1: Edge Offset Index Coding for LCU-based SAO [D.-K. Kwon, W.-S. Kim (TI)]
JCTVC-I0096 Non-CE1: Cross-check of edge offset index coding for LCU-based SAO [A. Fuldseth (Cisco)] [late]
JCTVC-I0292 Non-CE1: relocation of SAO syntax in interleaving mode [Y. Yasugi, T. Ikai (Sharp)]
JCTVC-I0210 Non-CE1: Crosscheck of Sharp's relocation of SAO syntax in interleaving mode in JCTVC-I0292 [C.-W. Hsu, Y.-W. Huang (MediaTek)] [late]
JCTVC-I0295 Non-CE1: On positive/negative sign for Category 1, 4 Edge Offset in SAO [H.-S. Song Song, C. Kim, J.-B. Choi, J.-H. Joo, K.-H. Lee, J. Kim (Samsung)]
JCTVC-I0192 Cross verification of JCTVC-I0295 from Samsung on Edge Offset signs signalling [G. Laroche, T. Poirier, P. Onno (Canon)] [late]
JCTVC-I0384 Non-CE1: Unified SAO interleaving syntax in APS and slice header [C.-W. Hsu, C.-M. Fu, C.-Y. Tsai, Y.-W. Huang, S. Lei (MediaTek)]
JCTVC-I0507 Non-CE1: Coding of SAO merge left and merge up [K. Minoo, D. Baylon (Motorola Mobility), I. S. Chong, M. Karczewicz (Qualcomm)] [late]

See notes in section discussing I0602.

JCTVC-I0599 Cross check of coding of SAO merge left and merge up (JCTVC-I0507) [E. Maani (Sony)] [late]
JCTVC-I0590 Supplementary test data on SAO type sharing between color components [E. Alshina, T. Lee, J.H. Park (Samsung), G. Laroche, T. Poirier, C. Gisquet, P. Onno (Canon)] [late]

Reviewed in Track A on Sunday evening 6 May.

In JCTVC-I0183, a proposal to share information between the U and V components was presented, reportedly allowing a reduction in SAO parameters for chroma components, as well as coding gains. The present informative contribution investigates sharing only the SAO type between the color components, which is asserted to offer opportunities for more efficient SAO implementation.

Further study was recommended.

JCTVC-I0601 Evaluation of combination of LCU SAO enable flag coding methods [W.-S. Kim, D.-K. Kwon (TI)] [late]

Reviewed in Track A on Sunday evening 6 May.

In this JCT-VC meeting, there have been several proposals dealing with signalling methods to turn off SAO. In JCTVC-I0193, an index is signalled to turn off Y, Cb, and Cr combinations, where one bin can be used to turn off SAO for all three color components for each LCU. In JCTVC-I0199, SAO on/off flag is signalled for each color component separately, and neighbouring LCUs are used to select context model. In JCTVC-I0184, SAO is turned off for the whole LCUs in a frame, based on the statistics of the previous frame.

In this document, the coding efficiency is investigated when these methods are combined. Experimental results reportedly show that the combined method of JCTVC-I0193 + JCTVC-I0199 can improve coding efficiency by 0.0%, 0.2%, and 0.9% for LCU size of 64, 32, and 16, respectively, for luma component compared to JCTVC-I0119 in case of low-delay B main, when interleaving mode is used.

The coding efficiency of the combination of JCTVC-I0193 + JCTVC-I0199 with JCTVC-I0184 is reported in this document as well. It was reported that this combination improves coding efficiency by 0.2%, 0.3% and 0.4% for LCU sizes of 64x64, 32x32, and 16x16, respectively, for luma component compared to JCTVC-I0184 in case of low-delay B main.

No action was taken on this.